Electronic current regulator



Ja'n. 20, 1959 c. H.` JONES ETAL ELECTRONIC CURRENT REGULATOR Filed Aug.14. -1953 RRR Q .CRN

United States Patent() ELECTRONIC CURRENT REGULATOR Charles H. Jones andJohn H. Thompson, Pittsburgh, Pa., assignors, by mesne assignments, tothe United States of'America as represented by the Secretary of the NavyApplication August 14, 1953, Serial No. 376,275

1 Claim. (Cl. 323-4) The invention described herein may be manufacturedby or for the Government of the United States of Amero ica forgovernmental purposes without the payment of any royalties thereon ortherefor.

This invention relates to a current regulator for continuous wavemagnetrons which transmit information by frequency and amplitudemodulation.

Both current and voltage regulators have four essential elements intheir circuitry, to wit: (l) An electron tube or regulator tube inseries with a load whose impedance may vary; (2) An amplifier foramplifying the corrcctive" signals; (3) An analyzer for observing thevoltage or current (depending upon the type of regulation desired); and(4) A reference voltage for comparison with the analyzed voltage.

It has been found that the voltage current performance curves ofcontinuous wave magnetrons are of such a nature that current regulationprovides greater stability than voltage regulation. The presentinvention, therefore, concerns itself specifically with means toregulate the current.

This invention, although not limited to such use, has been designedprimarily for use in connection with an airborne type of radarequipment. One of the essential features is the provision of a light,compact, easily operable type of unit which must, consequently, be asfree as possible from bulky, space wasting insulation while, at the sametime, it must be non-hazardous to the operating personnel.

In order to achieve the above, this circuit is so devised that thepositive side of the regulator output is at I ground potential, thischaracteristic being necessary if the shell or anode of the continuouswave magnetron is to be operated at ground potential. By the use of thiscircuit, current regulation is possible even with a shorted load zeroresistance. The arcing or sparking currents which may occur incontinuous wave magnetrons due to g-as within the tube, mismatch of theload, or

inadequate cathode temperature are limited to safe values.

so that the cathode destruction is minimized. In addition, the compositecircuit elements are all operated near ground potential. The regulatoramplifier, the voltage reference source, the voltage analyzer, and thecurrent regulator are all kept at safe operating potentials above ground(not over 300 volts). The cathode of the regulator tube is near groundpotential and the plate is 1000 volts above ground.

It is, therefore, one object of this invention to provide a currentregulator for continuous wave magnetrons which is non-hazardous tooperating personnel without the necessity of bulky insulation.

Another object of this invention is to provide a current regulator forcontinuous wave magnetrons which is light, compact and simple tooperate.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the saine 2,870,396 Patented Jan. 20,1959 becomes better understood by reference to the following detaileddescription when considered in connection with the accompanying drawingwherein:

Fig. l is a schematic diagram of a circuit embodying the invention.

Fig. 2 is a chart showing a regulation curve for a predetermined loadcurrent.

Referring now in greater detail to the drawing there is shown a circuitwherein a triode V1 is used to maintain a constant current across themagnetron. The triode V1 is in series with the magnetron which hasimpressed thereon a direct current voltage from a voltage source B. Thepositive potential of the voltage applied to the magnetron is groundedat G. The cathode of tube V1 is connected to the anode of the magnetronthrough resistor R1 so that the magnetron current must ow through V1.

The resistor R1 plus the magnetron are connected in parallel with avoltage divider network which includes resistors R2, R3, R4 and R5, apotentiometer R5 having a capacitor C1 shunted thereacross, and a pairof gas tubes V2 and V3 for regulating the voltage developed across thepotentiometer. The potentiometer is connected to the control grid of thepentode V4 through resistor R7, the plate circuit of the pentode havingplate resistors R8, R5, R10 and R11. The plate of the pentode isconnected to the grid of the tube V1 in order to regulate the biasthereof. A pair of voltage regulating glow tubes V5 and V5 are connectedto the screen grid of the pentode V4, the anode of tube V5 beingconnected to the voltage input through resistors R12, R13, R11, and R15while the cathode of V5 is at ground potential.

The operation of the system may be understood by assuming that themagnetron impedance decreases slightly. A current increase results fromthe impedance change and the potential across the resistor R1 increases.This increase in voltage appears on the control grid of the tube V4which, in turn, decreases the grid to ground potential on the tube V1.This results in an increase of the grid bias on the tube V1 which causesa decrease of the space current. In this way, the increase in the loadcurrent is almost eliminated. The screen voltage for tube V1 can besupplied from a low voltage positive supply or it can be connected tothe plate at V2. Either variation will eliminate the need for R12, R13,R14, R15, V5 and V5. Another modied form of the circuit is to eliminatethe R3, R1 and R5 and connect the cathode of V3 through the droppingresistor R2 to a low voltage negative supply (200 or 300 volts). Thiscompletely isolates the entire regulating circuit from the high negativevoltage.

A regulation curve is shown in Fig. 2 for a load current adjustment ofmilliamperes and various load voltages which were obtained by varyingthe load resistance. The internal effective impedance is greater than 20megohms.

Obviously may modifications and variations of the present invention arepossible in the light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claim the invention maybe practiced otherwise than as specifically described.

What is claimed as the invention is:

A current regular network for a load circuit having a pair of inputterminals said network comprising a high voltage supply source having apositive terminal and a negative terminal; means connecting one of theinput terminals of the load circuit to the negative terminal of thesupply source; means connecting the other input terminal of the loadcircuit to ground; a first electron tube having an anode, a cathode, anda control grid; a first resistor; means connecting the anode of Ythelfirst lectron tube to the positive terminal of the supply source; meansconnecting the cathode of the first electron tube to ground through therstresistor; a second electron tube having an anode, a cathode, Yandacontno'lgrid; means coupling the cathode of Atlietrst:electronytube-.to the control grid of ,thevsecond-electpon ,tuheynieans connecting the cathode of thefsecond electrontuhegtoggrqund; a secondresistor; means connecting the anode ,of the second electron tuhe `tothe positive terminal ,ofzthe As1 1pply source through the secondresistor; and means :also connecting the ,anode Vof the v,secondelectron wtube to the control grid .of the rst eleotrontube.

References Cited in the le of this patent UNITED STATES PATENTS Harnessetal May 17, 1932 Koch Apr. 23, 194() Braden Aug. 6, 1940 Vance Nov. 24,1942 Bowie f. Feb. 12, 1946 Blum'len Feb. 7, 1950 Gluyas Dec..25, 1951Evans v..;. -r Nov. 3, 19,53 Meszaros-----.` Dec. 28, 1954 Burdge Dec.V11, -1956

